Refractory article and method of making the same.



SILAS C. LINBARGER, F NIAfiARA FALLS, NEW YO, ASSIGNOR TO THE CARBORUN- DUM COMPANY, NIAGARA FALLS, NEW YORK, A CORPORATION OF PENNSYIE VIA.

newest.

No Drawing. I I

' To all whom iii-may camera: Be it known that I, SILAs G. LINBARGER, a citizen of the United States, residing at Niagara Falls, Niagara county, New York, .85 have invented a new and useful Improvement in Refractory Articles and Methods of Making the Same, of which the following is a full, clear, and exact description.

This invention has particular relation to refractory articles which contain graphite and silicon carbid. Graphite has long been used in the making of refractory articles, especially crucibles for the melting of metals. I have discovered that a mixture of 116 graphite, silicon carbid and clay produce a crucible of very superior refractory qualities. Such a mixture is very easy to mold and work in the plastic state, and after burning has a body which compared to the ac graphite" crucible is-more refractory, less oxidizible, of superior strengh, and ofhigh heat conductivity andgreat durability un'- der, abrasion and high temperature conditions.

As a typical mixture which may be emloyed for the production'of articles embodying my invention, I take natural ,flake or Ceylon graphite-43 parts; silicon carbid No. 40 and finer43 parts; and plastic fire clay14 arts; these proportions being I aphite is preferably by weight. he p crushed material 0 a,fineness'such that it will pass through about a No. 16 mesh. The

silicon carbid is run of .the mill crystalline 3 product, preferably containing 110 grit coarser than No. 4:0, and from this down 'to the finest powder, and i should be substantially' freejffrom carbon and other mpurities or"f oreign m'aterials. The clayj'is,

a good refractorygradeof plastic ma properly weathered or aged by mechanical means and analyzing aboutas follows:

I do not limit-myself to this particular 5@ clay however, as many cla s, of:- varying compositions will act as satisfactory binders. Furthermore, I do not limit myself to any exact size in the crushing of the siliconcarbid or the-graphite, and I have found as much finer grades ofsil' c ln carbid to give forming it to shape agalnst the walls of planes inthe walls of the crucible during REECTORY IIOLE AND METHOD OF MAKING THE SE. I

satisfactory results: Nor do I limit myself Specification of Letters Patent. p tgnt '7 1918, Application filed March 22, 1918. Serial at. 224,067.

to any exact proportions. The clay may be varied to obtain more .or less refractory composltions, or compositions which soften 1 at difi'erent temperatures, depending on the metal to be melted or the use proposed.

These materials are mixed with water and thoroughly worked in a pug mill until full plasticity of. the mixture is developed. In

the making of crucibles the well-kno wn form of crucible jigger is employed in the moldlngoperation, in'which-a plaster mold conforming to the outside dimensions of the crucible is revolved on the. head of the jig ger. A batch of the mixture is put in the mold and an inside fornfing tool is brought down within the mold and presses the material against the side of the mold at the same time spinning and working the material and.

the mold as the mold-revolves. The crucibles are then removed fromthe molds, dried .and fired in kilns in the usual manner. 1

The graphite employedshould be in flake or granular form, and for that. reason, natural graphite is preferred.

In the manufacture of graphite crucibles v the graphite particles or flakes have a tendency to aid'in forming cleavages or parting the molding operation as the materi slipping planes along which pieces of the crucible might. spall. off when put into use. On the contrary there is produced a very strong homogeneous structure.

The invention maybe applied to many 4 other refractory "articles, such as niuflies,

retorts, bricks, tubes and the like."

The refractory. articles produced by my process have many advantages over thoseproduced from graphite and clay alone.

The principal-advantage is they will stand sudden changes of temperature very successfully without cracking vor spalling.

. This is one very marked Weakness of ordinaryygraphite crucibles. Theheat conducti vit y'of'my com osition is very high, whwh means great fuel economy and ease of melting. SlllCOIl carbid is much less subject to oxidization than graphite'and the resistance of thecomposition to oxidization therefore is relatively high. The tensile strength is greater than that of ordinary graphite articles and it also resists abrasion very successfully.

I claim:

11 In the art of molding refractory mixtures of graphite and clay, the improvement which consists in adding crystalline silicon carbid grain in quantities suflicient to lesson or prevent the formation of parting planes in the body of the molded mass.

' 2. The herein described refractory article, I comprising graphite to a percentage above fifteen per cent. by weight, silicon carbid, and a bondin material.

3. The herein described refractory art1cle,

containing graphite in flake or granular foim rsilicon carbid, and clay.

. he herein described refractory article, containing graphite to a percentage above 'my hand.

SILAS c. LINBARGER. 

